07.27.10
Kimberly Newton
Marshall Space Flight Center, Huntsville, Ala.
256-544-6162
Kimberly.d.newton@nasa.gov
Rob Gutro
Goddard Space Flight Center, Greenbelt, Md.
301-286-4044
Robert.J.Gutro@nasa.gov
Sally Koris
Northrop Grumman Corporation, Redondo Beach, Calif.
310-812-4721
sally.koris@ngc.com
RELEASE: 10-094
JAMES WEBB SPACE TELESCOPE COMPLETES CRYOGENIC MIRROR TEST
HUNTSVILLE, Ala. – Recently, six James Webb Space Telescope beryllium
mirror segments completed a series of cryogenic tests at the X-ray &
Cryogenic Facility at NASA's Marshall Space Flight Center in
Huntsville, Ala.
During testing, the mirrors were subjected to extreme temperatures
dipping to -415 degrees Fahrenheit, permitting NASA contractor
engineers to measure in extreme detail how the shape of the mirror
changes as it cools.
With those measurements, the mirrors will be shipped to L-3
Communication, Tinsley in Richmond, Calif., for final surface
polishing at room temperature. Using those "surface error"
measurements, each mirror will then be polished in the opposite of
the surface error values observed, so when the mirror goes through
the next round of cryogenic testing, at Marshall, it should "distort"
into a perfect shape.
The facility at Marshall is the world’s largest X-ray telescope test
facility and a unique site for cryogenic, clean-room optical testing.
The next set of mirrors are due to arrive at NASA Marshall in August.
The Webb telescope has a total of 18 mirrors. Each of the 18 mirror
segments will be cryogenically tested twice in the Marshall Center's
X-ray & Cryogenic Facility to ensure that the mirror will maintain
its shape in a space environment -- once with bare polished beryllium
and then again after a thin coating of gold is applied.
The cryogenic test gauges how each mirror changes temperature and
shape over a range of operational temperatures in space. This helps
predict how well the telescope will image infrared sources.
The mirrors are designed to stay cold to allow scientists to observe
the infrared light they reflect using a telescope and instruments
optimized to detect this light. Warm objects give off infrared light,
or heat. If the Webb telescope mirror is too warm, the faint infrared
light from distant galaxies may be lost in the infrared glow of the
mirror itself. Thus, the Webb telescope's mirrors need to operate in
a deep cold or cryogenic state, at around -379 degree Fahrenheit.
Northrop Grumman is the prime contractor for the Webb telescope,
leading a design and development team under contract to NASA's
Goddard Space Flight Center in Greenbelt, Md.
The James Webb Space Telescope is NASA's next-generation premier space
observatory, exploring deep space phenomena from the formation of
distant galaxies to the behavior and interrelationships of nearby
planets and stars. The Webb telescope will give scientists clues
about the formation of the universe and the evolution of our own
solar system, from the first light after the Big Bang to the
formation of star systems capable of supporting life on planets like
Earth.
For more information about the James Webb Space Telescope, visit:
http://www.jwst.nasa.gov
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